Evaluation of Visual Implant Alphanumeric Tagging on Rio Grande Silvery Minnow

Abstract Visible implant alphanumeric (VIA) tags can be beneficial in studies where individual fish must be uniquely identifiable and other tagging methods are not feasible. We examined the feasibility of tagging the endangered Rio Grande Silvery Minnow Hybognathus amarus with VIA tags. We evaluated four key aspects related to VIA tagging in Rio Grande Silvery Minnow: 1) fish survival, 2) fish growth, 3) tag retention, and 4) tag legibility. Fish were randomly selected to be VIA tagged and were held in laboratory aquaria for 49 days. Visible implant alphanumeric tagged fish survival was high (96.7%), tag retention was low (36.2%), fish growth was not affected by tagging, and most retained tags were clearly legible (71.4%). Because of low tag retention and application difficulty, VIA tagging may not be applicable to large-scale field studies of small-bodied fishes.